With the remarkable development of wireless communication technologies, user demands are ever increasing. As users demand higher-capacity and higher-quality data transmission/reception, technologies using multiple antennas are being focused on. Beamforming technology refers to multiplying a response value of each antenna by a particular complex gain in order to obtain a large gain in a particular direction or channel using multiple antennas. The gain generated through such beamforming technology is referred to as a beam, and forming multiple beams in a plurality of directions or with a plurality of channels in one piece of user equipment or in one base station is called a multiple beam technology.
In order to serve multiple users using multiple beams, one base station transmits a signal corresponding to each user through one beam. At this time, each user receives both a signal through a desired beam and a signal through an undesired beam (interference). A technique of minimizing a gain in a direction corresponding to interference in order to reduce an interference signal is referred to as nulling. Since a user typically feeds back only the beam index (ID) having a high received-power level, a base station has difficulty in accurately identifying the location of the user. Accordingly, a point nulling technique for nulling a particular position is not practical in removing interference of beam communication. Furthermore, when the point nulling technique is used to simultaneously serve multiple users without removing interference, communication performance is significantly degraded. The convention technologies consider interference between neighboring cells but not intra-cell interference in simultaneously serving multiple users.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.